Engine-Airframe Integration for the Flying-V

The Flying-V is a novel flying wing concept where the main lifting surface has been fully integrated with the passenger cabin. Previous studies have focused on the aerodynamic and structural design of the airframe; but, prior to determining which engine-airframe integration alternative is most beneficial (e.g. boundary layer ingestion, distributed propulsion, and alike), an aerodynamic analysis of the engine installation effects needs to be performed. In this sense, engine integration studies require of complex models and a multidisciplinary approach to address the physics involved in the engine-airframe interaction phenomenon. In particular, the location of the engines around the airframe has a major impact on the overall aerodynamics of the aircraft. Hence, this study focuses on determining whether the aerodynamic efficiency benefits expected from this configuration are not offset by negative interferences with the nacelle, weight penalties, or regulation constraints. In order to do so, and initial benchmark for the lift to drag ratio is obtained from a baseline Flying-V configuration, and the influence of the x, y, and z coordinates, as well as engine orientation are analysed afterwards. To carry out the simulations, an Euler pressure-based solver on a three-dimensional-unstructured grid is used to model the flow at cruise condition: M = 0.85, h = 13000 m, α = 2.9 ◦ , and T = 50 kN, and the viscous drag contribution is computed following an empirical approach. A total of forty different engine locations are tested under these conditions to build a preliminary surrogate model that predicts the aircraft’s lift to drag ratio based on the position of the nacelle. The results obtained show that misplacing the engine can lead to significant lift to drag ratio losses going as high as 55% when compared against the ideal integration configuration. Finally, a region behind the airframe’s trailing edge is identified where the interference losses due to the installation are minimized. In light of the results obtained, a location is recommended for the engines where the perturbations observed on the lift to drag ratio are near the 10%, and a good compromise is obtained among the different requirements imposed.Aerospace Engineerin